Problem: Ana dives into a pool off of a springboard high dive. Her height (in meters above the water), $x$ seconds after diving, is modeled by $h(x)=-5(x+1)(x-3)$ How many seconds after diving will Ana hit the water?
Solution: Ana hits the water when $h(x)=0$. $\begin{aligned} h(x)&=0 \\\\ -5(x+1)(x-3)&=0 \\\\ \swarrow &\searrow \\\\ x+1=0\text{ or }&x-3=0 \\\\ x=-1\text{ or }&x=3 \end{aligned}$ We found that $h(x)=0$ for $x=-1$ or $x=3$. Since $x=-1$ doesn't make sense in our context, the only reasonable answer is $x=3$. In conclusion, Ana hit the water after $3$ seconds.